With the development of network technology, a lot of voice, data, video and other services can be transmitted by means of a network, so a demand for bandwidth is enhanced, and a Passive Optical Network (PON) emerges based on the demand.
FIG. 1 is a structural schematic diagram of a PON system according to a related art. As shown in FIG. 1, the PON system consists of an Optical Line Terminal (OLT) of an office-side, an ONU of a user-side, and an Optical Distribution Network (ODN), and generally adopts a point-to-multipoint network structure. The ODN consists of a single mode fiber, an optical splitter, an optical connector and other passive devices, and provides optical transmission media for a physical connection between the OLT and the ONU.
At present, PON technologies with a 40G transmission capacity mainly include a system for TWDM PON. FIG. 2 is a structural schematic diagram of a system for TWDM PON according to a related art; as shown in FIG. 2, each TWDM channel manages a group of ONUs. Uplink wavelengths of a group of ONUs for sending uplink data are the same, and downlink wavelengths for receiving downlink data are the same too. Different ONUs in each group of ONUs transmit the uplink data in a time division multiplexing mode. The downlink wavelengths of different TWDM channels are different, and the uplink wavelengths of each group of ONUs which are managed by different OLTs are different too. According to a command of the OLT, each ONU sends the uplink data in a specific time slot.
In deployment and application of the PON, some users have higher requirements on security and expect operators to provide a corresponding safeguard mechanism to ensure a rapid recovery from the interruption of a service channel. So a standby channel for protection is required for the PON which bears users' service operation.
FIG. 3 is a structural schematic diagram of protection switching of Type B according to the relate art; as shown in FIG. 3, the protection switching of the Type B presented in an existing PON standard can protect the OLT and a trunk fiber. Both of two optical ports PON (0) and PON (1) of the OLT are connected to a 2:N optical splitter, and the optical splitter is downwards connected to each ONU through the fiber. A channel through which the optical port PON (0) of the OLT reaches the ONU by means of the optical splitter is a master channel, and a channel which the optical port PON (1) of the OLT reaches the ONU by means of the optical splitter is a standby channel. After the master channel as a service channel of the ONU and OLT interrupts, the standby channel is enabled to maintain a communication between the ONU and OLT. In this technology, because the uplink wavelength and downlink wavelength of each channel adopt the same configuration, the ONU has no need to tune its uplink wavelength and downlink wavelengths.
It is observed during research that because each TWDM channel in the system for TWDM PON adopts a configuration of different uplink wavelengths and downlink wavelengths, in case of adopting a protection switching solution of the Type B, it is necessary to building a standby channel specially for each TWDM channel to provide service protection, thereby increasing the cost of deploying the PON system.
Aiming at a problem of high cost caused by specially building a standby channel for each TWDM channel in the system for TWDM PON to provide service protection, an effective low cost solution is not available.